Discovery may help defang viruses( Researchers may be able to tinker wit...)

Researchers may be able to tinker with a single amino acid of an enzyme that helps viruses multiply to render them harmless, according to molecular biologists who say the discovery could pave the way for a fast and cheap method of making vaccines.

"We have successfully tested this technique with poliovirus," said Craig Cameron, the Paul Berg professor of biochemistry and molecular biology at Penn State. "And we think it is applicable to most other viruses." Viruses have a simple mission; infect a cell, make more viruses, and then break out of the cell to infect more cells. This calls for fast and efficient multiplication. Viruses do this with the help of an enzyme called polymerase, whose main job is to assist in making more copies of the virus.

Once a virus infects a cell, there is a race against the clock between the virus, which is trying to multiply quickly, and the immune system trying to control the spread. A virus can cause disease and death if it can spread more rapidly than the immune system can neutralize it.

But if the body has been exposed to a vaccine weakened form of the virus in this case the body can respond more rapidly when it is exposed to the virulent strain. The key to developing vaccines is finding the one strain mutation that will prime the immune system without causing disease.

The Penn State researchers may have done just that. Cameron and his colleagues, Jamie Arnold and Christian Castro, both research associates, have identified a key amino acid in the polymerase of poliovirus that controls the speed and accuracy with which the virus is able to multiply.

By replacing this key residue with different amino acids, the researchers were able to generate mutants of the virus that are essentially harmless.

"We found that very subtle changes in the chemistry at this location of the polymerase has dramatic effects on weakening the virus," said Cameron, who has a provisional patent on the technique.

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